The "July phenomenon" is the putative adverse effect of inexperienced physician-trainees appearing in July on the inpatient units of teaching hospitals. Although the consequences of care by inexperienced physicians are a concern for both policy makers and consumers, little research has been done on this subject. With teaching hospital under increased pressure to reduce costs and to compete for patients, the need to answer such questions has become compelling. The purpose of our research will be to quantify the "July" effect (if any) on the cost and quality of inpatient care in Twin Cities teaching hospitals. We will use total charges, charges for diagnostic services, operating room charges, and length of stay as the dependent variables reflecting inpatient costs. Hospital mortality rate, nosocomial infection rate, and operative complication rate will serve as the dependent variables reflecting the quality of inpatient care. For each of these dependent variables we will test the hypothesis that Twin Cities teaching hospitals experience a change in the dependent variable from July to June which is significantly different from any change experienced by nonteaching hospitals over the same time period. In addition we will investigate whether any "July" effect experienced by teaching hospitals is more pronounced for the medical or surgical inpatient services. Finally, we will investigate whether the "July phenomenon" has become more or less pronounced in recent years.